Retroreflective structural colour film for smart displays and the preparation method thereof

Abstract

The present disclosure relates to an retroreflective structural colour film and a preparation method thereof. The main steps are as follows: (1) assembling colloidal microspheres to form a monolayer of microspheres; and (2) transferring the monolayer of microspheres onto a transparent substrate which has an adhesive layer to make the monolayer of microspheres partially embedded in the adhesive layer to prepare the retroreflective structural colour film. The retroreflective material has the advantages of the simple preparation process, high reflective brightness and uniformity of reflection colour. Moreover, the retroreflective material can exhibit unique retroreflective structural colour under the illumination of a white light source. These characteristics make the retroreflective material especially suitable for nighttime traffic safety applications, for example, to provide a constant colour signal to drivers, and simultaneously to provide dynamically changing colour signal to pedestrians to warn them of approaching vehicles.

What is claimed is: 
     
       1. A preparation method of retroreflective structural colour film, characterized in that specific steps are:
 (1) assembling colloidal microspheres to form a monolayer of microspheres on a surface of a substrate material by a self-assembly method, wherein a material of said colloidal microspheres is any one or any combination of following organic or inorganic components: polystyrene, polymethyl methacrylate, polyacrylic acid, polycarbonate, polyurethane, epoxy resin, silica, titanium dioxide, borosilicate, barium titanate and aluminum oxide; and 
 (2) transferring said monolayer of microspheres prepared in the step (1) onto a transparent substrate having an adhesive layer to make said monolayer of microspheres immersed in said adhesive layer to prepare said retroreflective structural colour film. 
 
     
     
       2. The preparation method according to  claim 1 , wherein a particle diameter of said colloidal microspheres is in a range of 1 μm to 1000 μm. 
     
     
       3. The preparation method according to  claim 1 , wherein said colloidal microspheres are microspheres with a uniform particle diameter or a mixture of microspheres with two or more particle diameters. 
     
     
       4. The preparation method according to  claim 1 , wherein the method for assembling said colloidal microspheres to form said monolayer of microspheres is any one of rubbing assembly method, liquid volatilization assembly method, interface assembly method, template assembly method, mechanical spraying method and spin coating method. 
     
     
       5. The preparation method according to  claim 1 , wherein said adhesive layer is a scotch tape. 
     
     
       6. The preparation method according to  claim 1 , wherein said transparent substrate is coated with the adhesive layer or coated with a viscous layer. 
     
     
       7. The preparation method according to  claim 1 , wherein said monolayer of microspheres being immersed in said adhesive layer means that said monolayer of microspheres is at least partially embedded into said adhesive layer.